1. Field of the Invention
The present invention relates to diagnostics and measurement of static and/or dynamic strains in structures, structural elements and structural materials, and particularly to a structural material with embedded sensors, the sensors being fiber Bragg grating sensors embedded in the structural material for strain measurement.
2. Description of the Related Art
There is an ever present need to provide either service monitoring of safety-critical components and structures or to optimize their usage, particularly if the structures or components are fabricated of composite materials. This need is particularly critical in the field of structures and components utilized for aerospace, naval and railway applications, and in the construction field (e.g. bridges, viaducts, oil ducts, offshore platforms, etc.). In such applications, the diagnostics need is paralleled by a requirement for reliable, miniaturized, portable monitoring systems.
Conventional sensors for measuring stress and strain that are formed from piezoelectric materials, magnetic materials or the like are typically relatively bulky and are susceptible to damage, or at least to interference from environmental conditions, such as temperature variations, electromagnetic fields and the like.
Optical sensors that are either attached to the component surface (i.e., the structure) to be monitored or embedded, where possible, are particularly suitable for such applications. Each of the above applications can benefit from the small, durable, long-lived, electromagnetically immune capabilities of optical fibers to implement the optical sensing function. Conventional optical sensors, however, are typically used in conjunction with other sensors, or are combined with other monitoring elements that also suffer from the above problems. It would be desirable to provide a purely optical sensor on or in the structural element to be monitored.
Thus, a structural material with embedded sensors solving the aforementioned problems is desired.